1. Field of the Invention
The present application relates to a catheter system, and, more particularly, to a percutaneous catheter system for transporting blood during surgical procedures.
2. Background of the Related Art
During surgical heart procedures such as bypass or valve surgery, blood is withdrawn from the venous side of the patient, transported through a heart lung machine where it is oxygenated, and returned to the patient's arterial side for distribution throughout the body. Thus, the heart is bypassed and the heart lung machine performs the pumping function of the heart. Typically, the blood is withdrawn by a venous catheter inserted into the right atrium or the vena cava and the blood is returned by an arterial catheter inserted into the aorta. The aorta must be clamped to isolate the left atrium and ventricle of the heart to prevent the returned blood from entering therein. Such clamping, however, can cause damage to the internal wall of the aorta as well as cause plaque to be separated from the aorta and enter the patient's bloodstream.
Conventionally, bypass procedures were performed by opening the sternum via a long incision in an invasive procedure, resulting in a lengthy recovery period for the patient. Arterial and venous access for the cannulas connecting to the heart lung machine, as well as cross-clamping the aorta, was achieved through the large opening in the sternum.
With the advent of minimally invasive surgical procedures which enabled heart surgery to be performed through a small window in the patent's chest or through cannulas inserted through small incisions between the ribs, the need existed for a minimally invasive way to achieve arterial and venous catheter access as well as to isolate the left side of the heart
European patent application 218,275 describes an arterial catheter for open heart surgery designed to avoid clamping the aorta by providing an inflatable balloon to occlude the blood vessel. The catheter includes a channel for the delivery of cardioplegia fluid into the heart to arrest the heart or for venting fluid from the heart and a separate channel to transport the blood from the bypass machine to the aorta. The application states that the balloon also has the advantage of keeping the tip of the catheter spaced from the vessel wall so the blood vessel tissue cannot obstruct blood flow through the catheter tip. The arterial catheter is described as being inserted into the aorta, near the aortic valve. In an alternate embodiment, the catheter's position in the aorta is reversed.
U.S. Pat. No. 5,312,344 to Grinfeld et al also discloses an arterial perfusion cannula designed to avoid the trauma of aortic clamps. The catheter has one or two balloons to occlude the arterial vessel in the ascending aorta between the aortic valve and the coronary ostium, a pathway for fluid to inflate the balloon, a pathway to transport blood from the bypass machine through the catheter, and a pathway for cardioplegia solution or venting. In one embodiment, the catheter is inserted through the ascending aorta and in an alternate embodiment it is inserted through the femoral artery.
U.S. Pat. No. 5,478,309 to Sweezer et al. also discloses an arterial catheter system having an occlusion balloon, a pathway for cardioplegia or venting, and a passage for blood flow. The occlusion balloon and pathway for cardioplegia are positioned on a second cannula which is slidably mounted within the blood flow cannula. Different methods of insertion of the catheters are described, namely insertion through the subclavian artery, through the femoral artery and directly into the aorta through a trocar port.
Insertion through the femoral artery and subclavian artery does provide a minimally invasive approach as it achieves access without a large opening in the chest cavity, However, since these arteries are small, insertion through these arteries requires a small catheter. Patients undergoing heart surgery have plaque buildup in the arteries which can obstruct insertion of the catheters. The plaque buildup further reduces the internal diameter of the artery. Also, the catheters, if too large, can scrape off the plaque and send it into the bloodstream, causing a stroke. Consequently, the foregoing affect the maximum feasible diameter of the catheter.
On the other hand, the minimum feasible diameter of the catheter is dictated by the fact that the catheter must have three separate pathways: for cardioplegia (and venting), balloon inflation and blood flow. The blood flow passage size is critical since it must be sufficient to return the blood to the patient undamaged.
Sweezer '309, in an attempt to limit the size of the catheter, describes a complex telescoping cannula arrangement. The catheter is of relatively large size since it must have an opening for blood flow, cardioplegia, balloon inflation and as well as a passageway to receive another cannula. Moreover, in Sweezer's femoral access approach, the blood is returned in a retrograde fashion, i.e. opposite the normal direction of blood flow, in a region of the body far removed from the aortic arch and the major vessels feeding the upper body. Thus, there is the risk that sufficient blood cannot be supplied to the upper regions of the body, e.g. the brain.
The need therefore exists for an arterial occlusion catheter system which has a large enough passage to return the blood, undamaged, to the patient's arterial side but is small enough to be inserted minimally invasively without the aforementioned adverse affects on the patient.